//手写类型判断
function myTypeOf(value){
    if (value === null) return 'null'
    //判断是否是引用类型
    if (typeof value === 'object') {
        let valueClass = Object.prototype.toString.call(value).slice(8, -1)
        return valueClass.toLowerCase()
    } else {
        return typeof value
    }
}

// console.log(myTypeOf())
let xx = {}
console.log(typeof xx)